RDTA-11 REPEAT STEREOTACTIC RADIOSURGERY FOR TREATMENT OF LOCALLY RECURRENT BRAIN METASTASES

Abstract With improvements in cancer treatment, patients are living longer and incidence of brain metastases (BM) is increasing. Stereotactic radiosurgery (SRS) has been shown to be safe and effective in the treatment of BM. Despite high local tumor control rates with SRS, there remains uncertainty regarding how best to treat BM recurrent following initial SRS. This study evaluates the outcomes of repeat SRS (rSRS) for BM that recur locally after initial SRS. Following institutional review board approval, we conducted a retrospective review of patients who received rSRS for BM that recurred locally following initial SRS. We identified 77 patients with 429 BM treated initially with SRS, of which 97 lesions underwent rSRS for local failure (LF). Of these, 49 lesions were treated with salvage resection followed by post-operative rSRS (surgery + rSRS). The median follow-up was 20.3 and 13.9 months from the initial SRS and rSRS, respectively. The median time between initial SRS and rSRS was 14.9 months. The median overall survival was 42.4 months (95% confidence interval [95% CI] 32.8-60.6) and 22.5 months (95% CI 15.6-40.2) from initial SRS and rSRS, respectively. There was no significant difference in local control after surgery + rSRS versus rSRS alone (p=0.3); the cumulative incidence of LF at 1 year was 11.1% (95% CI 4.0-22.31) versus 18.4% (95% CI 9.0-30.5) after surgery + rSRS versus rSRS alone, respectively. The cumulative incidence of symptomatic radiation necrosis (RN; Grade ≥2) was 1.17% (95% CI 0.5-2.6) at 1 year and 1.9% (95% CI 0.9-3.6) at 2 years after initial SRS, and 12.6% (95% CI 6.8-20.1) at 1 year and 18.2% (95% CI 11.1-26.7) at 2 years after rSRS. Our findings suggest rSRS is a viable salvage treatment option for recurrent BM, with comparable tumor control to initial SRS but with a higher risk of RN.